Altered muscle membrane potential and redox status differentiates two subgroups of patients with chronic fatigue syndrome

Table 1 Characteristics of the study population

	Group 1 (N = 39)	Group 2 (N = 33)
Age (years)	43 ± 3	47 ± 2
Weight (kg)	64 ± 2	68 ± 2
Sex ratio (F/M)	28/11	17/16
Onset of fatigue (months)	78 ± 19	69 ± 14
TBARS rest (nmol/ml)	1.36 ± 0.03	1.01 ± 0.05***
ORP (mV)	165 ± 5	127 ± 4***
VO₂max (mlO₂/min/kg)	19 ± 1	19 ± 1
VO₂max (% predicted)	67 ± 3	63 ± 3
Maximal work rate (W)	124 ± 5	118 ± 7
Maximal work rate (% predicted)	90 ± 3	83 ± 3
HR max (bpm)	151 ± 3	148 ± 3
Delta K⁺ max (mmol/l)	0.42 ± 0.07	0.65 ± 0.07**
Handgrip strength (N	278 ± 22	315 ± 33
Handgrip strength (% predicted)	62 ± 7	71 ± 7

Group 1 had marked changes in M-wave amplitude and duration whereas no M-wave changes were measured in group 2. All values shown are mean ± standard deviation
TBARS thiobarbituric acid reactive substance, ORP oxidation reduction potential, VO₂ oxygen uptake, HR heart rate
Maximal increase in plasma potassium (K⁺) concentration was measured at the end of exercise. Asterisks denote significant intergroup difference (**p < 0.01; ***p < 0.001)

ISSN: 1479-5876